随机字母数字字符串Linux Swift 3

在Linux中使用Swift 3生成随机字符串时，我遇到了两个问题

arc4random_uniform在Linux中仅在BSD上不可用。所以我可以不用使用random（）函数。当我生成一个可变大小的随机数时，这就起作用了（见下面的代码）

为linux修改的代码块

    func randomString(_ length: Int) -> String
    {

let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let len = letters.characters.count

var randomString = ""

#if os(Linux)

    for _ in 0..<length
    {
        let randomValue = (random() % len) + 1

        randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(randomValue))])"
    }

    #else
    for _ in 0 ..< length
    {
        let rand = arc4random_uniform(UInt32(len))

        randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(rand))])"
    }
    #endif


      return randomString
}          

func-randomString（u-length:Int）->String
{
let字母：String=“abcdefghijklmnopqrstuvxyzabcdefghijklmnopqrstuvxyz012456789”
让len=letters.characters.count
var randomString=“”
#如果操作系统（Linux）
对于uu0..1）始终使用相同的数字

您必须设置一次种子才能从
random（）
获取“随机”数：

:

如果未提供种子值，则将使用random（）函数
使用值1自动设定种子

由于种子总是相同的（1），所以总是得到相同的“随机”数序列

2）字母数字字符串

要创建字符串而不使用
NSString
：

func randomString(length: Int) -> String {

    let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let len = UInt32(letters.characters.count)

    var randomString = ""

    for _ in 0 ..< length {
        let rand = myCustomRandom(len)
        let randIndex = letters.index(letters.startIndex, offsetBy: Int(rand))
        let nextChar = letters[randIndex]
        randomString += String(nextChar)
    }

    return randomString
}

func randomString（长度：Int）->String{
let letter letters=“ABCDEFGHIJKLMNOPQRSTUVXYZABCDFGHIJKLMNOPQRSTUVXYZ0123456789”
设len=UInt32（字母.字符.计数）
var randomString=“”
对于uu0..<长度{
设rand=myCustomRandom（len）
设randex=letters.index（letters.startIndex，offsetBy:Int（rand））
让nextChar=字母[randIndex]
随机字符串+=字符串（nextChar）
}
返回随机字符串
}
找到了答案

因此，重复随机数/字符串的答案是在调用random（）函数之前添加这一行

srand(UInt32(time(nil)))

我假设这也是修复非法指令的原因，因为我不记得还改变了什么

不用说，这是我的最终结果

 func generateRandomNumber() -> Int
 {
    var place = 1

    var finalNumber = 0;

    #if os(Linux)

    srand(UInt32(time(nil)))

    for _ in 0..<5
    {
        place *= 10

        let randomNumber = Int(random() % 10) + 1

        finalNumber += randomNumber * place
    }
    #else
    for _ in 0..<5
    {
        place *= 10

        let randomNumber = Int(arc4random_uniform(10))

        finalNumber += randomNumber * place
    }
    #endif

     return finalNumber
 }



 func randomString(_ length: Int) -> String
 {

    let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let len = letters.characters.count

    var randomString = ""

    #if os(Linux)

    srand(UInt32(time(nil)))

   for _ in 0..<length
   {
     let randomValue = (random() % len) + 1

     randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(randomValue))])"
   }

   #else
  for _ in 0 ..< length
  {
     let rand = arc4random_uniform(UInt32(len))

     randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(rand))])"
  }
  #endif

   return randomString
 }  

func generateRandomNumber（）->Int
{
变量位置=1
var finalNumber=0；
#如果操作系统（Linux）
srand（UInt32（时间（零）））
对于uu0..我复制并粘贴了您的代码，但它无法编译

致命错误：无法从空字符串形成字符

以下是另一种方法：
这对我在Ubuntu上很有用。
Swift 4.2、Ubuntu 16.04

let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let len = letters.count
var randomString:String = ""
for _ in 0 ..< length {
   let rand = Int.random(in: 0..<len)
   randomString += letters.map { String($0) }[rand]
}

let字母：String=“abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzo123456789”
让len=字母数
var randomString:String=“”
对于uu0..<长度{
让rand=Int.random（in:0..感谢您的第一个答案，但是您提供的字母数字字符串部分不支持arc4random_统一，因为它在linux上。当然。您必须使用种子
random（）
。更新的答案。啊看起来不错。是因为它是swift 4吗？不，这没有使用任何swift 4功能。；）
func randomString(length: Int) -> String {

    let letters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let len = UInt32(letters.characters.count)

    var randomString = ""

    for _ in 0 ..< length {
        let rand = myCustomRandom(len)
        let randIndex = letters.index(letters.startIndex, offsetBy: Int(rand))
        let nextChar = letters[randIndex]
        randomString += String(nextChar)
    }

    return randomString
}

srand(UInt32(time(nil)))

 func generateRandomNumber() -> Int
 {
    var place = 1

    var finalNumber = 0;

    #if os(Linux)

    srand(UInt32(time(nil)))

    for _ in 0..<5
    {
        place *= 10

        let randomNumber = Int(random() % 10) + 1

        finalNumber += randomNumber * place
    }
    #else
    for _ in 0..<5
    {
        place *= 10

        let randomNumber = Int(arc4random_uniform(10))

        finalNumber += randomNumber * place
    }
    #endif

     return finalNumber
 }



 func randomString(_ length: Int) -> String
 {

    let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
    let len = letters.characters.count

    var randomString = ""

    #if os(Linux)

    srand(UInt32(time(nil)))

   for _ in 0..<length
   {
     let randomValue = (random() % len) + 1

     randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(randomValue))])"
   }

   #else
  for _ in 0 ..< length
  {
     let rand = arc4random_uniform(UInt32(len))

     randomString += "\(letters[letters.index(letters.startIndex, offsetBy: Int(rand))])"
  }
  #endif

   return randomString
 }  

// Keep at top of your code (outside of functions)
#if os(Linux)
    srandom(UInt32(time(nil)))
#endif


func getRandomNumber(_ min: Int, _ max: Int) -> Int {
    #if os(Linux)
        return Int(random() % max) + min
    #else
        return Int(arc4random_uniform(UInt32(max)) + UInt32(min))
    #endif
}


func getRandomString(_ chars: String, _ length: Int) -> String {
    var str = ""

    for _ in 1...length {
        str.append(chars.itemOnStartIndex(advancedBy: getRandomNumber(0, chars.count - 1)))
    }

    return str
}


// Best practice to define this outside of the function itself
let chars = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
print(getRandomString(chars, 10))

let letters : String = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789"
let len = letters.count
var randomString:String = ""
for _ in 0 ..< length {
   let rand = Int.random(in: 0..<len)
   randomString += letters.map { String($0) }[rand]
}